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//------------------------------------------------------------------------------
// <copyright file="DBSchemaTable.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
// <owner current="true" primary="false">Microsoft</owner>
//------------------------------------------------------------------------------
namespace System.Data.Common {
using System;
using System.Data;
using System.Data.ProviderBase;
using System.Diagnostics;
sealed internal class DbSchemaTable {
private enum ColumnEnum {
ColumnName,
ColumnOrdinal,
ColumnSize,
BaseServerName,
BaseCatalogName,
BaseColumnName,
BaseSchemaName,
BaseTableName,
IsAutoIncrement,
IsUnique,
IsKey,
IsRowVersion,
DataType,
ProviderSpecificDataType,
AllowDBNull,
ProviderType,
IsExpression,
IsHidden,
IsLong,
IsReadOnly,
SchemaMappingUnsortedIndex,
}
static readonly private string[] DBCOLUMN_NAME = new string[] {
SchemaTableColumn.ColumnName,
SchemaTableColumn.ColumnOrdinal,
SchemaTableColumn.ColumnSize,
SchemaTableOptionalColumn.BaseServerName,
SchemaTableOptionalColumn.BaseCatalogName,
SchemaTableColumn.BaseColumnName,
SchemaTableColumn.BaseSchemaName,
SchemaTableColumn.BaseTableName,
SchemaTableOptionalColumn.IsAutoIncrement,
SchemaTableColumn.IsUnique,
SchemaTableColumn.IsKey,
SchemaTableOptionalColumn.IsRowVersion,
SchemaTableColumn.DataType,
SchemaTableOptionalColumn.ProviderSpecificDataType,
SchemaTableColumn.AllowDBNull,
SchemaTableColumn.ProviderType,
SchemaTableColumn.IsExpression,
SchemaTableOptionalColumn.IsHidden,
SchemaTableColumn.IsLong,
SchemaTableOptionalColumn.IsReadOnly,
DbSchemaRow.SchemaMappingUnsortedIndex,
};
internal DataTable dataTable;
private DataColumnCollection columns;
private DataColumn[] columnCache = new DataColumn[DBCOLUMN_NAME.Length];
private bool _returnProviderSpecificTypes;
internal DbSchemaTable(DataTable dataTable, bool returnProviderSpecificTypes) {
this.dataTable = dataTable;
this.columns = dataTable.Columns;
_returnProviderSpecificTypes = returnProviderSpecificTypes;
}
internal DataColumn ColumnName { get { return CachedDataColumn(ColumnEnum.ColumnName);}}
internal DataColumn Size { get { return CachedDataColumn(ColumnEnum.ColumnSize);}}
internal DataColumn BaseServerName { get { return CachedDataColumn(ColumnEnum.BaseServerName);}}
internal DataColumn BaseColumnName { get { return CachedDataColumn(ColumnEnum.BaseColumnName);}}
internal DataColumn BaseTableName { get { return CachedDataColumn(ColumnEnum.BaseTableName);}}
internal DataColumn BaseCatalogName { get { return CachedDataColumn(ColumnEnum.BaseCatalogName);}}
internal DataColumn BaseSchemaName { get { return CachedDataColumn(ColumnEnum.BaseSchemaName);}}
internal DataColumn IsAutoIncrement { get { return CachedDataColumn(ColumnEnum.IsAutoIncrement);}}
internal DataColumn IsUnique { get { return CachedDataColumn(ColumnEnum.IsUnique);}}
internal DataColumn IsKey { get { return CachedDataColumn(ColumnEnum.IsKey);}}
internal DataColumn IsRowVersion { get { return CachedDataColumn(ColumnEnum.IsRowVersion);}}
internal DataColumn AllowDBNull { get { return CachedDataColumn(ColumnEnum.AllowDBNull);}}
internal DataColumn IsExpression { get { return CachedDataColumn(ColumnEnum.IsExpression);}}
internal DataColumn IsHidden { get { return CachedDataColumn(ColumnEnum.IsHidden);}}
internal DataColumn IsLong { get { return CachedDataColumn(ColumnEnum.IsLong);}}
internal DataColumn IsReadOnly { get { return CachedDataColumn(ColumnEnum.IsReadOnly);}}
internal DataColumn UnsortedIndex { get { return CachedDataColumn(ColumnEnum.SchemaMappingUnsortedIndex);}}
internal DataColumn DataType {
get {
if (_returnProviderSpecificTypes) {
return CachedDataColumn(ColumnEnum.ProviderSpecificDataType, ColumnEnum.DataType);
}
return CachedDataColumn(ColumnEnum.DataType);
}
}
private DataColumn CachedDataColumn(ColumnEnum column) {
return CachedDataColumn(column, column);
}
private DataColumn CachedDataColumn(ColumnEnum column, ColumnEnum column2) {
DataColumn dataColumn = columnCache[(int) column];
if (null == dataColumn) {
int index = columns.IndexOf(DBCOLUMN_NAME[(int) column]);
if ((-1 == index) && (column != column2)) {
index = columns.IndexOf(DBCOLUMN_NAME[(int) column2]);
}
if (-1 != index) {
dataColumn = columns[index];
columnCache[(int) column] = dataColumn;
}
}
return dataColumn;
}
}
}
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